ABSTRACT
Abstract Caries is a multifactorial disease that can negatively affect dental tissues through the demineralization process, which produces acids deriving from the metabolism of carbohydrates. Some strategies to prevent this process have been proposed, such as topical fluoride application, resin-based restorations, pit and fissures sealers, infiltrated resins, vaccines, mouthwashes, and several brushing techniques. Objective. To evaluate in vitro enamel hydrophobic modification as a method of prevention against demineralization. A descriptive and comparative study was carried out. Thirty premolars extracted for orthodontic reasons were obtained, encapsulated in epoxy resin, sectioned, and sanded to obtain specimens 3mm in thickness. The samples were pretreated with NaOCl and EDTA, incubated with 1 and 4% octadeyltrichlorosilane (OTS) or with 3 and 6% octadecyltriethoxysilane (TEOS) for 5min and for 8h. Subsequently, the samples were immersed in citric acid for 2 months. The samples were analyzed by their contact angle, infrared spectroscopy, scanning electron microscopy, atomic and confocal force, before and after treatment in citric acid. The samples coated with 1 and 4% OTS for 5min and 8h kept the silanizing agent on their surface after 2 months in citric acid. The treatment with TEOS was only effective at 6% with a reaction time of 5min. The modification with 1 and 4% OTS protects the surface of the tooth enamel from demineralization in acidic medium. The results indicate that treatment with 4% OTS is effective from 5min, which makes it appropriate in clinical practice.
Resumen Introducción. Caries es una enfermedad multifactorial que destruye en tejido dental por la desmineralización de ácidos generados en el metabolismo de carbohidratos. Algunos métodos preventivos, como fluoruro, resinas, selladores de fosetas y fisuras, resinas infiltradas, vacunas, enjuagues bucales, y un sinfín de técnicas de cepillado, han sido empleadas. Objetivo. Evaluar in vitro la modificación hidrofoba del esmalte como método preventivo en contra de la desmineralización. Materiales y Métodos. Un estudio decriptivo y comparativo fue empleado. Se obtuvieron treinta premolares sanos extraidos por razones ortodónticas y encapsulados en resina epóxica, seccionados y pulidos hasta obtener especímenes de 3mm de grosor. Las muestras fueron pretratadas con NaOCl y EDTA, incubadas en octadeciltriclosorilano (OTS) al 1 y 4% y octadeciltrietoxisilano (TEOS) 3 y 6% por 5min y 8h. Después, las muestras fueron sumergidas en ácido cítrico por 2 meses. Las muestras fueron analizadas con ángulo de contacto, espectroscopía infrarroja, microscopía electrónica de barrido, atómica y confocal, antes y después de tratamiento con ácido cítrico. Resultados. Las muestras cubiertas con OTS 1 y 4% por 5min y 8h mantuvieron el agente silanizante sobre la superficie después de 2 meses en ácido cítrico. El tratamiento con TEOS fue efectivo al 6% y con un tiempo de reacción de 5min. Conclusiones. La modificación con 1 y 4% de OTS proteje la superficie del esmalte dental contra la desmineralización en un medio ácido. Estos resultados indican que el tratamiento con OTS 4% es efectivo desde 5min de aplicación, lo cual es apropiado en la práctica clínica.
Subject(s)
Tooth Demineralization/prevention & control , Dental Caries , SilanesABSTRACT
BACKGROUND: At present, there is no uniform standard for the treatment time of chemical reagents for surface treatment of glass fiber posts. Therefore, studying the effect of treatment time of glass fiber post surface treatment reagents on the bond strength between fiber posts and resin cements is of great significance. OBJECTIVE: To evaluate the effect of two chemical agents on the bonding strength of glass fiber post and resin cement after surface pretreatment of glass-fiber posts at different times. METHODS: Forty-eight glass fiber posts were randomly divided into eight groups according to different surface treatment methods, six in each group. Group A received no special treatment; group B was treated with silanization for 1 minute; group C1 underwent a 30% hydrogen peroxide surface treatment for 5 minutes prior to 1-minute silanization; group C2underwent a 30% hydrogen peroxide surface treatment for 10minutes prior to 1-minutesilanization; group C3 underwent a 30% hydrogen peroxide surface treatment for 15 minutes prior to 1-minute silanization; group D1 underwent a 35% phosphoric acid surface treatment for 30 seconds prior to 1-minute silanization; group D2 underwent a 35% phosphoric acid surface treatment for 60 seconds prior to 1-minute silanization; group D3 underwent a 35% phosphoric acid surface treatment for 90 seconds prior to 1-minute silanization. The surface morphology of the treated glass fiber posts was observed under scanning electron microscope. The glass fiber post was bonded to the resin cement to form a cylindrical resin block and cut into a thin sample. The sheet was placed on a universal testing machine for micro-extrusion experiments. The failure mode of the specimens was observed under a stereomicroscope. RESULTS AND CONCLUSION: (1) Scanning electron microscope: the surface of the fiber post had different degrees of matrix dissolution and fiber bundle exposure after hydrogen peroxide and phosphoric acid treatment, but did not destroy the integrity of the fiber bundle. (2) Micro-extrusion experiments: the order of the bonding strength was as follows: group C3 > group C2 > group C1 > group D2 > groupD3 > groupD1> group B > group A, and there was significant difference between groups (P< 0.05) except for groups A and B, groups C2 andC3, and groups D2and D3. (3) Stereo microscope: the failure mode in the groups A and B was almost destruction in adhesion. The other six groups showed destruction in adhesion, but the cohesive failure and mixed failure were increased, and the failure mode changed from destruction in adhesion into cohesive failure and mixed failure. (4) These results indicate that the optimal treatment time of 30% hydrogen peroxide is 10 minutes, and the optimal treatment time of 35% phosphoric acid is 60 seconds. 30% hydrogen peroxide solution treatment of fiber post surface for 10 minutes has great clinical application value.
ABSTRACT
The purpose of the present study was to compare the influence of post-surface treatment with silane, hydrogen peroxide, hydrofluoric acid or sandblasting and to investigate the effect of silane in combination of the other treatments on the microtensile bond strength between fiber posts and composite resins for core build-up. Thirty-two glass-fiber posts (FRC Postec Plus, Ivoclar Vivadent, Schaan, Liechtenstein) were divided into eight groups according to the different surface pretreatments performed: silane application (S); immersion in 28% hydrogen peroxide (HP); immersion in hydrogen peroxide followed by application of silane (HP-S); immersion in 4% hydrofluoric acid gel (HF); immersion in hydrofluoric acid gel followed by application of silane (HF-S); sandblasting with aluminum oxide particles (SB); sandblasting followed by application of silane (SB-S). In control group, no surface treatment was performed. The composite resin (Tetric Flow, Ivoclar Vivadent, Schaan, Liechtenstein) was applied onto the posts to produce the composite cylinder specimen. It was sectioned into sticks to measure the microtensile bond strength. The data was analyzed with one-way ANOVA and LSD test for post hoc comparison (p < 0.05). Post pretreatment with sandblasting enhanced the interfacial strength between the fiber posts and core materials. Moreover, sand-blasting followed by application of silane appears to be the most effective method that can improve the clinical performance of glass fiber posts.